Light emitting semiconductor devices are broadly used to enhance performance and power consumption characteristics of various applications. There are numerous applications and systems, where light emitting semiconductor devices are used as light sources. The present invention relates to all kinds of those applications. Just one example is Liquid Crystal Display (LCD) backlighting. In LCD backlighting systems a light source is needed to shine through the semi-transparent panel. Accordingly, backlighting supports the use of liquid crystal displays for a broad variety of applications, for which the liquid crystal displays were otherwise not suitable. A cost effective architecture for such a system requires multiple light emitting diodes (LEDs). Typically a matrix of light emitting diodes is provided behind a liquid crystal panel to provide sufficient and uniform light over the panel's whole area. The matrix or array of LEDs consists of strings of LEDs in one orientation. The number of single LEDs per string may be as high as 40 or more. The total string draws a small current, for example, 50 mA driven by a large voltage, for example 80 V, being applied across the complete string of LEDs. According to a most simple configuration, the so called 0 dimensional dimming (0 D dimming) is applied, wherein multiple strings connected in parallel are driven from a common off-the-shelf power supply. By adding a linear regulated current source to each string, the current per string can be adjusted. This results in the 1 dimensional dimming (1 D dimming). Further, if an individual control of the current through each LED within a string is desired, a bypass switch is added to each LED known as 2 dimensional dimming (2 D dimming). Further, the electrical properties of the LEDs and the switches may vary due to production spread and aging. Accordingly, from a system point of view, the organization and the arrangement as well as the control of the light emitting diodes and the switches challenges those skilled in art in seeking power efficient, reliable and cheap solutions. The above considerations are not limited to backlighting systems, but they relate to all kinds of lighting systems using light emitting semiconductor devices.